Re: QRP-LABS Low Pass Filter upgrade


Timothy Fidler
 

It is possible to armour up say a 40 w PCB for a LP  filter  like the one from Far Ccts  (Also sold out of India  by Sunil Lakarami) with heavy Cu wire , solder stitched along  existinig traces.  you need to handle the bare wire with gloved hands so it does not get sweat on it so you can then spray it with Polyurethane varnish to protect the critical outer layer where RF will be travelling.  DO NOT flow solder all over the copper. you need bead welds of solder to the PCB trace every now and then. Obviously the CU is being run down the guts of the existing PCB trace.  Where you have vias in a PC B you will have to work out a solution.  Navships on Ebay sells TE insulated Cu wire 1.0 mm dia which can be a shovel out of hard place.  take care not to breath teflon fumes if soldering it.  Navships is also known as John's wire shop.  I don't believe he has any solid core wire greater than 1.0mm. TE insulated wire of any sort is a nice thing to have for this sort of duty. 

Sod's law - such a board will be sized for say type T50 toroids. If you want to move it to a HIGHER PLane you may get mechanical clashes. So a 5 filter PCB may turn into a 3 band PCB. " Ya get that on these big jobs"

regards, TE Fid

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